Printed circuit edge connector

ABSTRACT

A method and device defining a printed circuit edge connector wherein extruded plastic insulator bodies are utilized in forming the connector and the contact elements associated with the edge connector are inserted in or molded in the edge connector during formation thereof.

United States Patent Steigerwald Feb. 18, 1975 [5 PRINTED CIRCUIT EDGE CONNECTOR 3,550,246 12/1970 Zoller 29/413 3,618,207 11/1971 Sand et al. 29/629 [75] Inventor: Carl J. stelgerwald, Wauconda, 111. 3,672,046 7 6,1972 Storey 6 alum 29/627 73] Assignee: TRW lnc., Elk Grove Village, 111. 3,750,091 7/1973 Blackmail et 29/629 3,795,037 3/1974 Luttmer 29/629 [22] Filed: Sept. 12, 1973 [21] Appl. N0.: 396,556 Primary ExaminerC. W. Lanham Related US. Application Data Division of Ser. No. 228,099, Feb. 22, 1972, Pat. No. 3,795,049.

11.8. C1....; 29/629, 29/630 B, 29/630 D Int. Cl H02g 15/00 Field of Search 29/627 626, 629, 630 B,

References Cited UNITED STATES PATENTS 7/1968 Gannoe 29/630 C Assistant Examiner-James R. Duzan Attorney, Agent, or Firm-Lawrence S. Cohen [57] ABSTRACT A method and device defining a printed circuit edge connector wherein extruded plastic insulator bodies are utilized in forming the connector and the contact elements associated with the edge connector are inserted in or molded in the edge connector during formation thereof.

3 Claims, 9 Drawing Figures PRINTED CIRCUIT EDGE CONNECTOR This application is a division of copending application Ser. No. 228,099 filed Feb. 22, 1972, now US. Pat. No. 3,795,049.

The present invention relates to an improved method for making edge connectors adapted for use in conjunction with printed circuits and, more particularly, is useful in the manufacture of edge connectors quickly and economically.

In one form of the inventive concept a printed circuit edge connector may be defined utilizing low cost extruded plastic insulator material and simple, formed wire contacts associated with the insulator body to define the completed edge connector assembly. The contact element of the connector assemblies may be integrally formed with the insulating body or otherwise injected intothe insulating body in a separate operation, as desired.

Edge connectors, of course, are commonly known in the art. For example, in the military field gold plated contact elements are associated with a relatively hard thermo setting resin as the insulating body. It will be readily recognized that edge connectors manufactured in this manner are relatively expensive and cannotbe involved in a market suitable for relatively low cost commercial products such as television, office machines, vending machines, and the like. It is important in many military products and in the computer field, of course, to have substantially absolute reliability of all such components. In the relatively low cost commercial field this aspect is not as important and, accordingly, certain compromises may be accepted to permit reduction in manufacturing and production cost of the articles so that it will be available to the consumer market at a price which is competitive and acceptable for the product involved.

Edge connectors commonly known are manufactured withthe use of hard plastic materials such as thermo setting resins. In these materials it is common to mold the insulating body with openings therein to receive the contact elements. The contact elements must be formed in a manner to permit them to lock in the insulating body when they are separately inserted within the molded openings within the body. Still other forms of manufacture of edge connectors with a hard resin material involve the drilling or punching of openings within the resin to provide means for introduction of electrically conductive elements within the insulating body. Steps ofthis character, of course. introduce a significant expense in the manufacturing and assembly cost and result in a characteristic high cost production item. Accordingly, such articles are utilized only in assemblies where high reliability is involved and where the overall expense of the item is relatively high to carry the cost of such relatively high cost components of the system.

The present invention involves a relatively simple concept for the manufacture of edge connectors using relatively soft plastic materials wherein the contact elements of the edge connector are inserted during or immediately after extrusion of the insulating body without the use of pre-formed contact elements.

It is, accordingly, a primary object of the present invention to provide an improved edge connector which is relatively inexpensive to fabricate and which is substantially reliable in use.

Other objects and advantages of the present inventive concept involve the provisionof an improved method for the making of edge connectors and the provision of edge connectors made by the method set forth herein which is economical to manufacture, reliable in use, readily adapted to present manufacturing processes and which is an economically defined finished product adapted for commercial use in relatively low cost products.

The novel features which are believed to be characteristic in the inventive concept are set forth with particularly in the appended claims. The invention itself, however, together with further objects and advantages thereof will best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective schematic illustration of a connector assembly made in one form of the inventive concept set forth herein;

FIG. 2 is a schematic illustration, in part, and defining the means for manufacture of the edge co-nector of the type schematically illustrated in FIG. 1;

FIG. 3 is a schematic illustration of one step in the manufacture of an edge connector of the type illustrated schematically in FIG. 1 showing the wire connector just prior to insertion into the insulating body;

FIG. 4 is a schematic illustration of a successive step in the manufacture of an edge connector of the type illustrated in FIG. 1 wherein the wire lead is inserted fully through the insulating body and the terminal thereof has been bent to define the connector configuration extending within the shielded portion of the insulating body;

FIG. 5 is a schematic illustration of the next step in the assembly of the connector of the type schematically illustrated in FIG. 1 wherein the wire connector lead is withdrawn into the insulating body so that the bent portion thereof is within the shielded portion of the insulating body and the outboard terminal extends outboard of the rear or base portion of the insulating body and is bent so that the general longitudinal axis thereof extends normally to the horizontal base plane of the rear of the insulator body of the connector;

FIG. 6 is a schematic illustration of another form of manufacture of a connector assembly commonly char acterized as an edge connector wherein the contact elements are embedded within the insulator body during extrusion of the insulator body;

FIG. 7 is a sectional elevation of the edge connector assembly schematically represented in FIG. 6 showing the contact elements in position in the insulating body;

FIG. 8 is a fragmentary view of the contact elements, in strip form, utilized in making the edge connector assembly schematically illustrated in FIG. 6 with the top and bottom strips still associated with the contact elements to maintain the spaced-apart connector elements in properly indexed relation; and

FIG. 9 is a schematic illustration of means and the method for forming the connector assembly schematically illustrated in FIG. 6 with the connector elements being presented in the form assembly during extrusion of the insulating body in manufacture.

One of the inventive concepts specifically set forth herein contemplates the assembly of a printed circuit edge connector utilizing low cost extruded plastic insulator body and simple formed wire contact elements associated with the connector assembly. The assembly 3 n contemplates the use of basic components in the form of the continuous extruded profile and coil of wire to define the contact elements of the assembly. These components are assembled with relatively inexpensive and simple, and readily available, equipment to define a means for producing edge connectors in large quantities and relatively low cost.

In one form of the inventive concept, the contact element of the edge connector assembly will be stitched" in the insulator body; bent to the desired shape and then cut off of a coil of wire utilized in the assembly process. The insulator then will be indexed to the next contact position desired and'these steps repeated until a completed connector assembly is formed. The insulator body may be cut off from the remaining extrusion at any pre-determined length to define a completed connector assembly and another series of contact insertions may be initiated to continue the manufacture assembly.

The extrusion profile associated with the inventive concept set forth herein is provided so that a completed connector assembly may be mounted in several ways. For example, end clips may be added to guide the printed circuit board into the connector and to define means for a snap-fit of the connector to a mother board where it will be waive-soldered into place. In another form, the connector may be snap-fitted into a metal chassis utilizing the logitudinal grooves along both sides of the insulating body as defined in the drawings and characertized herein and the contact elements may be associated with external circuitry by suitable wire wrap connector elements electrically connected to the tails of the contacts associated with the edge connector boards. In still another form of the inventive concept, connectors may be used in very long lengths and plugged onto the edge of a large printed circuit board with the leads associated with the connector being bent to any configuration to accept a wire wrap, or mating receptacle. It should be noted that slots may be cut into the bottom of the connector element which will mate with tabs on the master board for locking and keying of the assembly, as desired.

An edge connector in one form of the inventive concept contemplated herein is schematically illustrated at in FIG. 1 of the drawings. The edge connector 10 involves an insulating body 12 and electrical contact elements 14 inserted within and associated with the insulating body 12.

The insulating body 12 is defined in the form of an extrusion which can be put into a suitable machine adapted for the purpose and the electrical contact element 14 then inserted with, again, an appropriate apparatus. The contact elements are simply defined in the form of wire and may be taken from a continuous coil associated with the apparatus.

An example of the method of insertion of electrical contact elements 14 may be seen from the schematic illustration set forth in FIGS. 2, 3, 4 and 5 of the drawings herein. The extrusion, or insulating body 12, is placed into an appropriate holding apparatus and the contacts 14 then are inserted into the extrusion at spaced intervals along the insulating body 12. The contact elements 14, as noted above, are defined from a simple formed wire and may be fed from the reel of wire (not shown) and fed to a punch or insertion device 16, as schematically illustrated in FIG. 2. The insertion device 16 is intended to grasp a portion of the reel of wire with a pre-determined length extending axially from the device 16. The extended portion of the wire is inserted into the insulating body 12 at a predetermined position therein by merely punching the contact through the wall of the insulating material as schematically suggested in the drawing of FIG. 3. The wire 14 is sufficiently rigid to force itsway through the relatively soft body of material defining the insulator '12 and is inserted to a point where the free terminal of the wire extends for a slight distance beyond the shielded tunnel-like portion of the insulating body 12, substantially as illustrated in FIG. 4 of the drawings.

The free terminal of the contact element then is deformed slightly to form a slight curvilinear portion along and extending away from the free end of the contact element 14, as illustrated in FIG. 4. The wire then is withdrawn so that the curvilinear portion on the free terminal of the contact element 14 is withdrawn into the shielded or tunnel-like portion of the insulator body 12 and will be substantially in the position illustrated in FIG. 5 of the drawings. The wire then is cut to the desired length and the portion extending from the rear of the insulator body 12 is then bent so that it extends normally to the general base line of the back of the insulator as illustrated by the dashed lines in FIG. 5 of the drawings.

The assembly of the edge connector is continued by simply indexing the inserting device 16 to the next position, inserting the next piece of wire and carrying through the same steps outlined above until a number of contact elements have been inserted into the insulating body and defined in the form illustrated or, in any other form desired by the user. It can readily be sent that the contact assembly made on the form and with the method illustrated herein is defined by simply stitching the contact elements into the insulating body 12 with the use of wire from a conventional wire coil rather than using pre-formed contacts which is what is normally being done at the present.

The inventive concept proposed here involves automatic assembly and the manufacture of edge connector assemblies without the use of pre-formed contact elements.

It can readily be seen from the drawings and the description set forth above that the contact elements 14 are simply inserted from the back side of the insulator body 12 on an angle so that they project through the opening in the connector insulating body 12. A curl or bend then is placed in the wire. The wire then is drawn back into the shielded, or tunnel-like, portion of the insulating body 12 until it is in the final position illustrated in FIG. 5 of the drawings. It should be observed that the wire moves quite readily around the curled edge of the insulating body to withdraw into the shielded portion of the insulating body 12. The back portion of the wire then is severed and the tail-like portion extending from the base of the insulating body 12 is bent so that it extends normally to the horizontal base plane of the back portion of the insulating body 12 as' illustrated by the dashed lines of FIG. 5. The insertion device 16, or the extrusion 12, then is indexed into the next position and the device 16 places the next contact 14 through the insulating body 12 and the forming operations described above are carried out to define the next indexed contact in the edge connector assembly. It should be noted that formed opendings are not defined in the insulator body but, rather, the opening is defined by insertion of the contact element itself serving as a punch and the plastic material used for the insulating body 12 is sufficiently resilient to tightly hold the contact element 14 in position in the insulating body 12 for use in the completed edge connector assembly.

It should be observed that assembly of edge connectors in the manner described herein may be performed in a manner which will permit insertion ofa plurality of contact elements 14 simultaneously rather than individually as described for purposes of illustration. For example, if the edge connector assembly as com pleted is to be provided with contact elements 14 it may be readily appreciated that an insertion device 16 would be provided forthe simultaneous insertion of the total number of contact elements at the same time by punching the elements through the base of the insulating body 12, forming them with the curve as illustrated in FIG. 4, and then withdrawing the contact elements so that the curved portion lies within the shielded portion of the edge connector body 12. The portion of the edge connector wire extending beyond the base of the assembly will be severed and will be bent as illustrated in FIG. 5 and the completed assembly will be defined. It should be noted also that contact elements may be inserted along either side of the insulating body 12 so that spaced apart contact elements will be provided in the event the edge connector assembly is to be provided to define contact with printed circuit elements on either side of an insulating board inserted into the edge connector.

It can readily be appreciated that the manufacture of edge connectors in the manner described herein results in the provision of a product which is relatively low in cost compared to the previous methods in the manufacture of edge connectors. Accordingly, the cost of the product is reduced to a point where the edge connector may be suitable for use in commercial products such as in television, office machines, vending machines, and the like. The previous method of manufacturing edge connectors involved the casting, or forming, of relatively hard insulating bodies. Openings were defined in the insulating body during manufacture or were drilled or punched in the insulating body after manufacture to receive contact elements. Moreover, gold plated contact elements frequently were used since the edge connectors were manufactured at a relatively high cost and the resultant product was intended for use in military products or in computers where reliability is an absolute requirement and cost is a secondary requirement. In addition to the above steps described in the previous manufacture of edge connectors, it was and is common to use pre-formed contact elements which individually are inserted into openings in the insulating body of the connector. It can readily be appreciated that this method of manufacture results in an expensive product which is not attractive in the manufacture' of products for commercial use where price is an important element of concern.

It should be noted that various wire shapes and sizes have been employed in the method described herein and that various plastic materials have been utilized all indicating that the method defined is equally adapted to a variation in wire shapes and sizes and with various plastics. Some of the plastic materials which have been employed in an experimental basis utilizing the concepts set forth herein are nylon, polypropylene, polycarbonate and PVC. All of these materials are equally adapted to use in the inventive conce pt described herein as the insulating body 12.

We have employed insulating body thicknesses of about one-sixteenth inch to approximately one-eighth inch and found that the wire body is sufficiently rigid to readily penetrate the insulating body material and is tightly grasped by the insulating body to define a rigid. complete edge connector assembly when made in accordance with the method described herein.

A modified concept for the production of inexpensively manufactured printed circuit edge connectors involves the use of an extruded profile insulator with the contact elements being extruded into the plastic and being presented therein during the extruding operation. This may be done with the use of perforating. or previously defined ribbons of copper or aluminum alloy (for example) having elongated slots therein as described below.

The contact element ribbons are extruded simultaneously with the insulating body as described below and then are separated by removing top and bottom carrier strips associated with the ribbons. Any plastic flash which may be on the contact surfaces may readily be removed by chemical solvents or mechanical abrasion. The connector assemblies then may be cut to length and fitted with mounting hardware or slotted to accept locking tabs on mating printed circuit boards, as desired.

A connector assembly of the type generally described above is shown in FIG. 6 of the drawings with the top and bottom assembly strips associated with the connector elements being joined to the connector ribbons.

In the method proposed herein the contact elements would be defined in a long strip or coil of metal which would be pre-punched (or otherwise defined) so that the ribbon or strip would have vertical ribs extending between top and bottom connector elements. The vertical ribs are generally illustrated at 20 in FIG. 6 with the top and bottom connectors 22 and 24, respectively, extending between the spaced apart vertical ribs orcontact elements 20 to hold them in spaced apart, rigid relationship for the assembly and forming operation. The vertical ribs 20, of course, eventually will define the electrical contact of the edge connector assembly and the connecting strips 22 and 24 extending across the top and bottom of the vertical strips to act as a carrier during assembly will be removed.

As seen in FIG. 6 the vertical ribs, or contact elements, 20 are positioned within the insulating body 26 in the manner set forth below. The manner of manufacture or extrusion of the assembly shown in FIGS. 6 and 7 is illustrated in FIG. 9.

As shown in FIG. 9 of the drawings a simple crosshead may be adapted for use with an extrusion machine. The cross-head is generally illustrated at 28 in FIG. 9 with a first portion 30 carrying soft-heated plastic material to the extrusion head or barrel] of the cross-head 28. A back guide plate 32 is secured to the barrel] of the cross-head 28 with an appropriate assembly device 34, as illustrated. An insert guide plate 36 and extrusion plate 38 are secured to the opposite end of the barrel of the cross-head 28 with a suitable holding ring 40, as illustrated in FIG. 9.

The metal strips are fed through the back guide plate in a continuous manner and during the feeding operation will appear substantially as schematically illustrated in the fragmentary view of FIG. 8 of the drawings. That is, the strips as fed to the extrusion head of the assembly apparatus will be defined with a slight curvature and will have vertical ribs extending between the top and bottom connector plates 22 and 24, respectively. The strips continue through the back plate 32 and into the barrel] of the cross head 28 of the extrusion apparatus where the resin, or insulating material, is picked up and formed about the strips in the barrel]. The strips are continuously moving through the barrel and move into the insert guide plate and through the extrusion plate 38 of the cross-head 28 and are pushed out of the cross head with the resin molded thereabout in an extruded fashion. The top and bottom carrier strips 22 and 24, respectively, then may be removed since the vertical strips 20 defining the contact elements of the assembly are rigidly secured within the plastic body of the insulating material 26 as schematically represented in FIGS. 6 and 7 of the drawings. The plastic flash then may be removed from the inner faces of the contact elements 20 by passing a grinding wheel or buffer along the area between the spaced apart contact elements 20 to move against this surface and remove any plastic that may be contained on the surfaces to provide means for good electrical contact during use of the edge connector assembly.

The temperature of extrusion will vary with the characteristics of the plastic being used to define the insulator body 26. Generally, the temperature involved will range from 200-300F which is an acceptable temperature for pre-tinned brass contacts of the type which may be employed in the making of edge connectors by the method defined herein.

We have found that the slight curvature defined in the strip illustrated schematically in FlG. 8 of the drawings is desirable in that the strip will move through the extrusion die in a more controlled fashion. Theslight curvature will, of course, lend some stability to the strip as defined and will prevent buckling or distortion of the strip as it moves through the extrusion die. The strips in spaced apart relation may be indexed in a manner so that the contact ribbons 20 which are across from each other may be in spaced apart relation within or .005 inch. This provides for economical manufacture of the edge connector and defines means for indexing the strips so that the spaced apart contact elements are within acceptable tolerance levels for commercial use.

in both of the forms of the invention set forth herein the wire sections employed in manufacture of the edge connector assemblies probably would be about 0.15 inch thick and about .030 inch wide and would have a generally D shaped cross section configuration. The reason for the shaped cross section is that in the event the wire is cur or abraded during assembly into the insulating body 12 or 26, it will not have a sharp corner biting into the copper on the printed circuit board since the generally D shaped configuration will provide a radius of curvature to the contact on the mating printed circuit board. The back, or tail, portions of the wires should contain some sharp corners which would be on the face away from the curved or D shaped portion so that the edge connectors may be employed with conventional wire wrap techniques rather than requiring soldering of all connectors. Accordingly, a D shaped configuration will give us smooth contact surfaces while still providing sharp corners for wire wrap techniques, as desired.

While I have shown and described a specific embodiment of the present invention it will, of course, be understood that other modifications and alternative constructions may be used without departing from the true spirit and scope of this invention. I therefore intend by the appended claims to cover all such modifications and alternative constructions as fall within their true spirit and scope.

What I claim, is:

1. An improved method for manufacture of edge connector assemblies having electrical contact elements embedded therein, said method comprising steps of:

forming a continuous strip of electrical contact elements in which the contact elements are oriented in parallel spaced apart relationship and are joined at, at least one end, by a carrying strip;

passing the continuous strip of electrical contact elements through an extruding means in which an insulating body of plastic material is continuously extruded in combination with the strip of contact elements;

forming an extruded assembly in which the contact elements are partially embedded within the insulating body and are partially exposed at opposite ends, and in which the carrying strips are exposed; removing the carrying strips; and

separating the extruded assembly into predetermined lengths for use as edge connectors.

2. The method of claim 1 wherein the contact elements are defined in a continuous strip being joined at the top and bottom by carrying strips and wherein after the formation of the edge connector assembly with the contacts embedded within the insulating body, the top and bottom carrying strips are removed so that theterminal portion of the contact elements are flush with the front edge of the edge connector assembly and a portion of the contact element extendssubstantially beyond the back edge of the connector assembly to provide means for joining of the contact elements to associated circuitry.

3. The method of claim 1 wherein the continuous strips of the edge connector assembly are provided with a slight radius of curviture to provide stability for the strips as the strips move through the extrusion apparatus during assembly of the edge connector. 

1. An improved method for manufacture of edge connector assemblies having electrical contact elements embedded therein, said method comprising steps of: forming a continuous strip of electrical contact elements in which the contact elements are oriented in parallel spaced apart relationship and are joined at, at least one end, by a carrying strip; passing the continuous strip of electrical contact elements through an extruding means in which an insulating body of plastic material is continuously extruded in combination with the strip of contact elements; forming an extruded assembly in which the contact elements are partially embedded within the insulating body and are partially exposed at opposite ends, and in which the carrying strips are exposed; removing the carrying strips; and separating the extruded assembly into predetermined lengths for use as edge connectors.
 2. The method of claim 1 wherein the contact elements are defined in a continuous strip being joined at the top and bottom by carrying strips and wherein after the formation of the edge connector assembly with the contacts embedded within the insulating body, the top and bottom carrying strips are removed so that the terminal portion of the contact elements are flush with the front edge of the edge connector assembly and a portion of the contact element extends substantially beyond the back edge of the connector assembly to provide means for joining of the contact elements to associated circuitry.
 3. The method of claim 1 wherein the continuous strips of the edge connector assembly are provided with a slight radius of curviture to provide stability for the strips as the strips move through the extrusion apparatus during assembly of the edge connector. 